| Castel Gandolfo to Orangevale (California) | 6,168.57 mi (9,927.35 km) |
| Castel Gandolfo to Orchards (Washington) | 5,795.02 mi (9,326.19 km) |
| Castel Gandolfo to Orcutt (California) | 6,366.46 mi (10,245.83 km) |
| Castel Gandolfo to Oregon (Ohio) | 4,660.56 mi (7,500.44 km) |
| Castel Gandolfo to Oregon (Wisconsin) | 4,847.15 mi (7,800.74 km) |
| Castel Gandolfo to Oregon City (Oregon) | 5,816.97 mi (9,361.51 km) |
| Castel Gandolfo to Orem (Utah) | 5,783.83 mi (9,308.17 km) |
| Castel Gandolfo to Orinda (California) | 6,243.47 mi (10,047.89 km) |
| Castel Gandolfo to Orland Park (Illinois) | 4,843.61 mi (7,795.03 km) |
| Castel Gandolfo to Orlando (Florida) | 5,128.46 mi (8,253.45 km) |
| Castel Gandolfo to Ormond Beach (Florida) | 5,081.54 mi (8,177.95 km) |
| Castel Gandolfo to Oro Valley (Arizona) | 6,185.97 mi (9,955.36 km) |
| Castel Gandolfo to Oroville (California) | 6,131.08 mi (9,867.02 km) |
| Castel Gandolfo to Oshkosh (Wisconsin) | 4,767.34 mi (7,672.30 km) |
| Castel Gandolfo to Oskaloosa (Iowa) | 5,047.26 mi (8,122.78 km) |
